Let's ask a question first: Why use non-metallic ones if the pipeline is equipped with metal compensators?
Friends who have been in contact with power plants and cement plants know that metal parts can't bear corrosion and dust accumulation in high-temperature flue gas pipelines and desulfurization systems. Although the metal bellows has high strength, it will rust out in a few months when it encounters acidic medium and wet smoke. Non-metallic compensators use fabric fibers, rubber, PTFE and other materials to deal with these "soft knives". This site'sNon-metallic expansion joint (fabric fiber expansion joint)Andrubber compensatorIt is to make up for the shortcomings of metal parts-to put it bluntly, it is to wear a layer of "body armor" on the pipeline.
The structure is actually not complicated
A flexible loop strap, plus flanges, frame and insulation. The band material may be silicone cloth, fluororubber,PTFE (rubber PTFE compensator)。 The key lies in design: how can it be resistant to both temperature and pressure? Generally, multi-layer composite, inner layer insulation, outer layer sealing. Two days ago, a customer asked: YouRectangular non-metallic expansion jointDifference from round? To put it bluntly, rectangles are mainly used in square pipes such as smoke ducts, which have large compensation and convenient installation-and the four corners of rectangular pipes are prone to stress concentration, which can be digested by the flexibility of non-metals.
Function Article 1: Absorb multidimensional displacement
During thermal expansion and contraction, the pipe will expand and contract axially, yaw laterally and even twist angularly. Because of its flexibility, the non-metallic compensator can absorb the displacement in these directions at the same time, and is not afraid of twisting like metal bellows. Like those used in the cement industryMetal Corrugated Expansion Joints in Cement IndustryAlthough it can also be compensated, when encountering large rectangular flues, non-metallic rectangular expansion joints are more cost-saving and easier to maintain. Think about it, when the temperature of a flue dozens of meters long changes, the displacement is often more than ten millimeters or even tens of millimeters, and the metal parts will get stuck directly if they are not properly designed. The non-metallic band is like a "soft joint", which is not afraid of twisting.
Function 2: Carry high temperature, carry corrosion, and reduce noise
The pipeline behind the desulfurization flue gas baffle door of the power plant is not high in temperature, but the acid corrosion is serious, and the metal parts will rust through in a few months. useNon-metallic expansion joints (fabric fiber expansion joints)With PTFE lining, the life can be extended by two or three years. In addition, it has a vibration damping effect-the vibration of the fan is transmitted to the pipeline, and the non-metallic band can eat some energy, and the noise is low. Some data show that under the same working conditions, the non-metallic compensator can reduce the noise of pipeline system by 8~12 dB. Tsk, this thing is easier than a silencer.
Compared with metal compensators, what are the advantages of non-metal?
Low pressure capacity, cannot be used in high pressure steam pipeline. Moreover, non-metallic materials will age, and their life span generally has to be replaced after 3-5 years. What about that? Calculate clearly when selecting: the medium temperature exceeds 600℃ or the pressure exceeds 0.1MPa, and honestly use metal parts orHigh temperature axial expansion joint； Low temperature and low pressure, large diameter, corrosive media, non-metal is the first choice. Is that the truth?
Finally, a reminder of the main points of purchasing
The national standard JB/T 12235-2015 stipulates the technical requirements of non-metallic expansion joints, mainly depending on the material of the ring belt, compensation amount and connection mode. Pay attention to the direction of the guide tube during installation-refer to the Q&AArrow direction of expansion jointThe tie rod nut should be adjusted according to the on-site displacement, and do not screw it (see for detailsHow to adjust the tie rod nut of expansion joint）。 If you are not sure, you can compare this siteUniversal corrugated expansion jointAndRectangular non-metallic expansion jointProduct parameters, or just ask the technology – they have more experience than me.
In summary, the role of a universal non-metallic compensator? It is to solve the "difficult and complicated diseases" that metal compensators can't handle: high-temperature corrosion, multi-dimensional displacement, large-diameter special-shaped pipes, vibration and noise reduction. If you choose the right one, the equipment is worry-free; Wrong choice, post-maintenance is enough for you to drink a pot.